Oxazolidinium Compounds and Use as Hydrate Inhibitors

ABSTRACT

Oxazolidinium compounds are formed by the reaction of a halohydrin or an epoxide with a secondary amine and an aldehyde or a ketone. The oxazolidinium compounds are formed directly and do not require the reaction of a pre-formed oxazolidine with an alkylating agent. The compounds are useful as gas hydrate inhibitors in oil and gas production and transportation.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 60/866,253 filed Nov. 17, 2006.

TECHNICAL FIELD

The invention relates to oxazolidinium compounds and methods for makingthem, and most particularly relates, in one non-limiting embodiment, tooxazolidinium compounds useful for inhibiting the formation ofhydrocarbon hydrates during the production of oil and gas, and directmethods for making such oxazolidinium compounds.

BACKGROUND

A number of hydrocarbons, especially lower-boiling light hydrocarbons,in formation fluids or natural gas are known to form hydrates inconjunction with the water present in the system under a variety ofconditions—particularly at the combination of lower temperature andhigher pressure. The hydrates usually exist in solid forms that areessentially insoluble in the fluid itself. As a result, any solids in aformation or natural gas fluid are at least a nuisance for production,handling and transport of these fluids. It is not uncommon for hydratesolids (or crystals) to cause plugging and/or blockage of pipelines ortransfer lines or other conduits, valves and/or safety devices and/orother equipment, resulting in shutdown, loss of production and risk ofexplosion or unintended release of hydrocarbons into the environmenteither on-land or off-shore. Accordingly, hydrocarbon hydrates have beenof substantial interest as well as concern to many industries,particularly the petroleum and natural gas industries.

Hydrocarbon hydrates are clathrates, and are also referred to asinclusion compounds. Clathrates are cage structures formed between ahost molecule and a guest molecule. A hydrocarbon hydrate generally iscomposed of crystals formed by water host molecules surrounding thehydrocarbon guest molecules. The smaller or lower-boiling hydrocarbonmolecules, particularly C₁ (methane) to C₄ hydrocarbons and theirmixtures, are more problematic because it is believed that their hydrateor clathrate crystals are easier to form. For instance, it is possiblefor ethane to form hydrates at as high as 4° C. at a pressure of about 1MPa. If the pressure is about 3 MPa, ethane hydrates can form at as higha temperature as 14° C. Even certain non-hydrocarbons such as carbondioxide, nitrogen and hydrogen sulfide are known to form hydrates undercertain conditions.

There are two broad techniques to overcome or control the hydrocarbonhydrate problems, namely thermodynamic and kinetic. For thethermodynamic approach, there are a number of reported or attemptedmethods, including water removal, increasing temperature, decreasingpressure, addition of “antifreeze” to the fluid and/or a combination ofthese. The kinetic approach generally attempts (a) to prevent thesmaller hydrocarbon hydrate crystals from agglomerating into larger ones(known in the industry as an anti-agglomerate and abbreviated AA) and/or(b) to inhibit and/or retard initial hydrocarbon hydrate crystalnucleation; and/or crystal growth (known in the industry as a kinetichydrate inhibitor and abbreviated KHI). Thermodynamic and kinetichydrate control methods may be used in conjunction.

Kinetic efforts to control hydrates have included use of differentmaterials as inhibitors. For instance, onium compounds with at leastfour carbon substituents are used to inhibit the plugging of conduits bygas hydrates. Additives such as polymers with lactam rings have alsobeen employed to control clathrate hydrates in fluid systems. Thesekinetic inhibitors are commonly labeled Low Dosage Hydrate Inhibitors(LDHI) in the art. KHIs and even LDHIs are relatively expensivematerials, and it is always advantageous to determine ways of loweringthe usage levels of these hydrate inhibitors while maintaining effectivehydrate inhibition.

Thus, it is desirable if new gas hydrate inhibitors were discoveredwhich would yield comparable or improved results over known gas hydrateinhibitors, and it is also desirable to find new ways of forming gashydrate inhibitors.

Oxazolidinium compounds are generally known in the art. They are knownto be formed by ring expansion of aziridinium compounds (N. J. Leonard,et al., Journal of Organic Chemistry, Vol. 28, p. 2850+ (1963)), andalso by the alkylation of preformed oxazolidines (U.S. Pat. Nos.5,427,774 to R. K. Chaudhuri, et al. and 5,132,377 to S. Nakano, etal.). More direct methods of forming oxazolidinium compounds are notknown.

SUMMARY

There is provided, in one form, a method for preparing an oxazolidiniumcompound that involves reacting an aldehyde and/or a ketone with asecondary amine and a halohydrin and/or an epoxide under reactionconditions sufficient to produce an oxazolidinium compound.

In another non-limiting embodiment herein, there is provided anoxazolidinium compound prepared by a method that involves reacting analdehyde and/or a ketone with a secondary amine and a halohydrin and/oran epoxide, under reaction conditions sufficient to produce anoxazolidinium compound. The oxazolidinium compound may have thestructure:

where R is a hydrocarbon substituent containing from 1 to 20 carbonatoms, and may be optionally substituted with heteroatoms such asoxygen, nitrogen, phosphorus and combinations thereof. R₁ and R₂ eachindependently have 1 to 20 carbon atoms, may be linear, branched orcyclic and may be optionally substituted with alkyl groups, aryl groups,alkylaryl groups, and aryl groups substituted with alkoxy groups. X ischlorine, fluorine, bromine and/or iodine.

In a different non-restrictive embodiment, there is presented a methodfor inhibiting formation of hydrocarbon hydrates that involvescontacting a fluid containing a mixture of water and hydrate-formingguest molecules at gas hydrate forming conditions with an amount ofoxazolidinium compound effective to inhibit formation of hydrocarbonhydrates at the conditions. The oxazolidinium compound is prepared by amethod involving reacting an aldehyde and/or a ketone with a secondaryamine and a reactant that is a halohydrin and/or an epoxide, underreaction conditions sufficient to produce an oxazolidinium compound.Alternatively or in addition thereto, the oxazolidinium compound mayhave the structure (I) above.

DETAILED DESCRIPTION

In the present invention there are included methods and compositionsused herein for inhibiting, retarding, mitigating, reducing, controllingand/or delaying formation of hydrocarbon hydrates or agglomerates ofhydrates in fluids used in hydrocarbon recovery operations. The methodmay be applied to prevent or reduce or mitigate plugging of annularspaces, pipes, transfer lines, valves, and other places or equipmentdownhole where hydrocarbon hydrate solids may form under conditionsconducive to their formation or agglomeration.

The term “inhibiting” is used herein in a broad and general sense tomean any improvement in preventing, controlling, delaying, abating,reducing or mitigating the formation, growth and/or agglomeration ofhydrocarbon hydrates, particularly light hydrocarbon gas hydrates in anymanner, including, but not limited to kinetically, thermodynamically, bydissolution, by breaking up, by anti-agglomeration other mechanisms, orany combination thereof. Although the term “inhibiting” is not intendedto be restricted to the complete cessation of gas hydrate formation, itmay include the possibility that formation of any gas hydrate isentirely prevented.

The terms “formation” or “forming” relating to hydrates are used hereinin a broad and general manner to include, but are not limited to, anyformation of hydrate solids from water and hydrocarbon(s) or hydrocarbonand non-hydrocarbon gas(es), growth of hydrate solids, agglomeration ofhydrates, accumulation of hydrates on surfaces, any deterioration ofhydrate solids plugging or other problems in a system and combinationsthereof.

The present method is useful for inhibiting hydrate formation for manyhydrocarbons particularly including hydrocarbon and non-hydrocarbonmixtures. The method is particularly useful for lighter or low-boiling,C₁-C₅, hydrocarbon gases, non-hydrocarbon gases or gas mixtures atambient conditions. Examples of such gases include, but are notnecessarily limited to, methane, ethane, ethylene, acetylene, propane,propylene, methylacetylene, n-butane, isobutane, 1-butene,trans-2-butene, cis-2-butene, isobutene, butene mixtures, isopentane,pentenes, natural gas, carbon dioxide, hydrogen sulfide, nitrogen,oxygen, argon, krypton, xenon, and mixtures thereof. These molecules arealso termed hydrate-forming guest molecules herein. Other examplesinclude various natural gas mixtures that are present in many gas and/oroil formations and natural gas liquids (NGL). The hydrates of all ofthese low-boiling hydrocarbons are also referred to as gas hydrates. Thehydrocarbons may also comprise other compounds including, but notlimited to CO, CO₂, COS, hydrogen, hydrogen sulfide (H₂S), and othercompounds commonly found in gas/oil formations or processing plants,either naturally occurring or used in recovering/processing hydrocarbonsfrom the formation or both, and mixtures thereof.

More specifically, the oxazolidinium compounds herein would be usefulhydrate inhibitors in many fluids involved in hydrocarbon recoveryoperations including, but not limited to, drilling fluids, drill-influids, workover fluids, completion fluids and the like. Suitable saltsfor forming the brines of these fluids include, but are not necessarilylimited to, sodium chloride, calcium chloride, zinc chloride, potassiumchloride, potassium bromide, sodium bromide, calcium bromide, zincbromide, sodium formate, potassium formate, ammonium formate, cesiumformate, and mixtures thereof.

Suitable gas hydrate inhibitors for use in the methods and fluidcompositions herein may include, but are not necessarily limited to,certain oxazolidinium compounds. The oxazolidinium compounds may havethe structure:

where R is a hydrocarbon substituent containing from 1 to 20 carbonatoms, and may be optionally substituted with heteroatoms selected fromthe group consisting of oxygen, nitrogen, phosphorus and combinationsthereof; R₁ and R₂ each independently have 1 to 20 carbon atoms, and maybe linear, branched or cyclic and may be optionally substituted withalkyl groups, aryl groups, alkylaryl groups, and aryl groups substitutedwith alkoxy groups. X may be chlorine, fluorine, bromine or iodine andcombinations thereof. These oxazolidinium compounds are believed to benovel compositions of matter.

A particularly useful oxazolidinium compound falling within thedefinition of structure (I) above, in turn has the structure:

where R is a C14 linear alkyl (or may be C12 or a mixture of the two),R₁ and R₂ are each n-butyl substituents, and X is chlorine.

Generally, the oxazolidinium compounds are prepared by reacting analdehyde and/or a ketone with a secondary amine and a halohydrin and/oran epoxide, under reaction conditions sufficient to produce anoxazolidinium compound. Suitable reaction conditions include atemperature ranging from about ambient to about 120° C., inclusive, anda pressure ranging from about ambient to the pressure required to keepthe reactants and solvents in the liquid phase, inclusive. In analternative, non-restrictive embodiment, the reaction temperature mayrange between ambient and about 90° C. The oxazolidinium compounds areformed directly and do not require the reaction of a pre-formedoxazolidine with an alkylating agent as in some prior preparationmethods.

With respect to reactant proportions, in some cases, up to 10 molequivalents of one or two reactants may be used. In other cases, up to 2mol equivalents of one or two reactants may be used. However, the idealreactant ratios are often one mol equivalent of halohydrin (or epoxide)with one mol equivalent of aldehyde (or ketone) with one mol equivalentof secondary amine.

In one non-limiting embodiment, a suitable aldehyde reactant isformaldehyde. Alternatively, the aldehyde may be one having 1 to 20carbon atoms and the ketone may be one having 3 to 20 carbon atoms.Specific, suitable aldehydes may include, but are not necessarilylimited to, formaldehyde, pivaldehyde (trimethylacetaldehyde) and/orbenzaldehyde, and the like. Specific, suitable ketones may include, butare not necessarily limited to, acetone, butanone and/or acetophenone,and the like.

Suitable halohydrins for use herein may have the general formula:

where X is chlorine, fluorine, bromine or iodine; and where R_(A),R_(B), R_(C) and R_(D) are each independently selected from the groupconsisting of hydrogen, hydrocarbon substituents containing from 1 to 20carbon atoms, and heteroatoms selected from the group consisting ofoxygen, nitrogen, phosphorus and combinations thereof. If R_(A), R_(B),R_(C) and R_(D) are heteroatoms, their remaining valences may beoccupied with H atoms.

Suitable epoxides for use in the methods and compositions hereininclude, but are not necessarily limited to, glycidyl ether, phenylglycidyl ether, bisphenol A diglycidyl ether, alkyl glycidyl ethershaving 1 to 20 carbon atoms, epoxides of alpha olefins containing 2 to20 carbon atoms, and the like.

Suitable secondary amines for forming the oxazolidinium compounds hereininclude those having 2 to 20 carbon atoms, and may be linear, branchedor cyclic and may be substituted with alkyl groups, such asdiethanolamine, aryl groups such as furfuryl or phenyl, alkylaryl groupssuch as benzyl, and/or aryl groups substituted with alkoxy groups suchas paramethoxyphenyl. Suitable secondary cyclic amines include, but arenot necessarily limited to compounds such as pyrrolidine or morpholineand the like.

The contacting of the oxazolidinium gas hydrate inhibitors herein withthe mixture of hydrocarbon, water and hydrate-forming guest moleculesmay be achieved by a number of ways or techniques, including, but notnecessarily limited to, mixing, blending with mechanical mixingequipment or devices, stationary mixing setup or equipment, magneticmixing or other suitable methods, other equipment and means known to oneskilled in the art and combinations thereof to provide adequate contactand/or dispersion of the composition in the mixture. The contacting canbe made in-line or offline or both. The various components of thecomposition may be mixed prior to or during contact, or both. Theoxazolidinium gas hydrate inhibitor should be prepared or formed priorto addition to the mixture or liquid that has potential for hydrateformation. If needed or desired, the oxazolidinium compound may beoptionally removed or separated mechanically, chemically, or by othermethods known to one skilled in the art, or by a combination of thesemethods after the hydrate formation conditions and/or hydrate-formingspecies are no longer present.

Because the present compositions and methods are particularly suitablefor inhibiting hydrate formation by lower boiling hydrocarbons orhydrocarbon and/or non-hydrocarbon gases at ambient conditions with nomore than five carbon atoms, the pressure of the hydrate-formingcondition is usually at or greater than atmospheric pressure (i.e.greater than or equal to about 101 kPa), in one non-limiting embodimentgreater than about 1 MPa, and in an alternate version greater than about5 MPa. The pressure in certain formations or processing plants or unitscould be much higher, say greater than about 20 MPa. There is nospecific high pressure limit. The present method can be used at anypressure that allows formation of hydrocarbon gas hydrates.

The temperature of the condition for contacting is usually below, thesame as, or not much higher than the ambient or room temperature. Lowertemperatures tend to favor hydrate formation, thus requiring thetreatment with the present compositions. At much higher temperatures,however, hydrocarbon hydrates may not form, thus obviating the need ofcarrying out any treatments.

It will be appreciated that it may be difficult to predict in advancethe proportions of oxazolidinium gas hydrate inhibitors herein effectivein inhibiting hydrocarbon hydrate formations in a particular fluid anygiven situation. There are a number of complex, interrelated factorsthat must be taken into account in determining the effective dosage orproportion, including, but not necessarily limited to, the proportion ofwater in the fluid, the nature of the hydrocarbon, the nature of thehydrate-forming guest molecules, the temperature and pressure conditionsthat the mixture of hydrocarbon and water are subject to, the particularhydrocarbon hydrate inhibitor employed, etc. Experimentation with aparticular set of conditions or in a specific system may be a suitableway to determine the optimum dosage range. Care should be taken to avoidthe formation of problematic quantities of irreversible, harmful hydratemasses. Nevertheless, in the interest of attempting to provide somegeneral guidance of effective proportions, relative to the water phase,the amount of the hydrate inhibitor is about 10 volume % or less,alternatively 8 volume % or less, and in another non-limiting embodimentis less than 6 vol %. In one non-limiting embodiment the lower limit isindependently about 0.01 volume %, and alternatively is about 0.1 vol %and possibly is about 0.5 vol %.

In addition to the gas hydrate inhibitor herein, the hydrocarboninhibitor composition and the fluid being treated may further compriseother additional components, including, but not limited to, differentcontrolling chemistries such as corrosion inhibitors, wax inhibitors,scale inhibitors, asphaltene inhibitors and other gas hydrate inhibitorsand/or solvents. Suitable solvents for the gas hydrate inhibitors hereinmay include, but are not limited to water; at least one oxygenatedcompound selected from C₁-C₆ alcohols, C₂-C₆ glycols, C₁-C₆mono-aliphatic, in one non-limiting embodiment mono-alkyl, ethers ofC₂-C₆ glycol, glycerin, C₁-C₆ mono-aliphatic, suitably mono-alkyl,ethers of glycerin, C₁-C₆ di-aliphatic, particularly dialkyl, ethers ofglycerin, glycerin esters of C₁-C₆ carboxylate; N-methylpyrrolidone;sulfolane; C₃-C₁₀ ketones, and mixtures thereof. Examples of acceptablesolvents in one non-limiting embodiment include water and liquidoxygenated materials such as methanol, ethanol, propanol, glycols likeethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, glycerin,esters and ethers of glycerin, CELLOSOLVE® (2-ethoxyethanol), CELLOSOLVEderivatives, 2-propoxyethanol, 2-isopropoxyethanol, 2-butoxyethanol,2-isobutoxyethanol, 2-methoxyethanol, ethoxylated propylene glycols,ketones such as cyclohexanone and diisobutylketone, and mixturesthereof. The solvent is present in the total hydrocarbon hydrateinhibiting composition in the range of from 0 wt % to about 85 wt %,alternatively from about 0 wt % to about 65 wt %, of the totalcomposition, based on volume. CELLOSOLVE is a registered trademark ofUnion Carbide Corporation.

Because some of the oxazolidinium gas hydrate inhibitor disclosed hereinwill be solids or gummy-like amorphous organic materials under ambientconditions, it is often helpful to use a suitable solvent as describedabove in the composition. This allows the formation of a homogeneous oruniform solution, suspension, emulsion or a combination of these, of allthe components for easier mixing or distributing or dispersing thecomposition in the hydrocarbon/water fluid or system to be treated. As aresult, more efficient and/or favorable contacting of the compositionwith the mixture comprising water and the hydrate-forming guestmolecules may be effected.

The present invention also may be used in combination with other methodsor processes, which have been known to one skilled in the art asdiscussed in the background to help inhibit formation of hydrates. Thecompositions and methods will now be further illustrated with respect tospecific Examples which are intended to further illuminate the inventionbut not limit it in any way.

PREPARATORY EXAMPLE 1

In a 4 ounce (0.12 liter) vial were placed 9.01 g of a chlorohydrinderived from epichlorohydrin and ALFOL 1214 (trade name for a mixture ofdodecyl and tetradecyl alcohols) 3.99 g of di-n-butylamine, 2.51 g of 37aqueous formaldehyde and 4.00 g of methanol as a solvent. The vial wasloosely capped with aluminum foil, sealed in a stainless steel pressurevessel, and pressurized to 150 psig (1.03 MPa) with nitrogen. Thepressure vessel was placed in an oven at 120° C. for 20 hours. Thepressure vessel was allowed to cool to room temperature and vented. Thevial contained a clear water soluble amber liquid. NMR analysisconfirmed the conversion of starting materials to an oxazolidiniumcompound.

HYDRATE INHIBITION EXAMPLES 2-5

The following components were tested for gas hydrate inhibitionefficacy: RE4394—a current, commercial hydrate inhibitor product, andComposition A—a dilution of the inventive oxazolidinium compound ofExample 1.

The various compositions were tested under the conditions shown in TableI. The liquid hydrocarbon used was from a proprietary location and knownto have hydrate formation concerns at the test conditions. The followingobservations may be made:

At subcooling of 36° F. (2.2° C.), no hydrate morphology control wasobserved for RE 4394 and Composition A.

At subcooling of 25° F. (−3.9° C.), all three show hydrate control atlow water cut.

The rankings are conducted on an A-F system where A is best and F isworst. LDHI refers to Low Dosage Hydrate Inhibitors; LH refers to“liquid height”.

TABLE I Gas Hydrate Inhibitor Testing Goals: Test RE 4394 & CompositionA Target: 1300 psig (8.96 MPa) @ 40° F. (9.4° C.) Cell 2 3 4 5 LDHI RE4394 @ Comp. A @ RE 4394 @ Comp. A @ 2.5 Vol % 2.5 Vol % 1.5 Vol % 1.5Vol % Liquid 50 vol % 50 vol % 75 vol % 75 vol % Hydrocarbon Phase GasPhase 15/85 15/85 15/85 15/85 Propane/Methane Propane/MethanePropane/Methane Propane/Methane Brine DI Water, 6 mL DI Water, 6 mL DIWater, 3 mL DI Water, 3 mL Observations Condensate is slightlyCondensate is slightly Condensate is slightly Condensate is slightlybefore cool- turbid; Upon contact brine turbid; Unable to turbid; Unableto turbid; Unable to down being transparent; Little determine theclarity of determine the clarity of determine the clarity of smallcrystal observed on brine, but only slightly brine, but only slightlybrine, but only slightly the wall even at RT for turbid at worst; Fineturbid at worst; Fine turbid at worst; Fine short time whitish layer atliquid whitish layer at liquid whitish layer at liquid interfaceinterface interface LH (mm) >32 >32 >32 >32 Chiller Temperature 1.5°C. - Bath Temperature 37° F. (2.8° C.) Observations Large chunk ofhydrates Large chunk of hydrates Large chunk of hydrates Large chunk ofhydrates @ 16.00 hr adhering to cell's interior, adhering to cell'sinterior, adhering to cell's interior, adhering to cell's interior, andblock ball move; Little and block ball move; Little and block ball move;Little and block ball move; Little condensates observed condensatesobserved condensates observed condensates observed LH (mm) n/a n/a n/an/a Ranking F F F F Chiller Temperature 5° C. - Bath Temperature 42° F.(5.6° C.) Observations Large chunk of hydrates Large chunk of hydratesLarge chunk of hydrates Large chunk of hydrates @ 40 hr adhering tocell's interior, adhering to cell's interior, adhering to cell'sinterior, adhering to cell's interior, and block ball move; Little andblock ball move; Little and block ball move; Little and block ball move;Little condensates observed condensates observed condensates observedcondensates observed LH (mm) n/a n/a n/a n/a Ranking F F F F ChillerTemperature 8.5° C. - Bath Temperature 48° F. (8.9° C.) ObservationsLarge chunk of hydrates Dispersion of tiny Dispersion of tiny Dispersionof tiny @ 48 hr adhering to cell's interior, hydrates in condensatehydrates in condensate hydrates in condensate and block ball move;Little and water; Both balls rock and water; Both balls rock and water;Both balls rock condensates observed with ease; Clear two with ease;Clear two with ease; Clear two phase observed. phase observed. phaseobserved. LH (mm) n/a >32 >32 >32 Ranking F B A A

PREPARATORY EXAMPLE 6

The inventive oxazolidinium compounds may be made from an epoxide by aprocedure such as the following. In a 2 ounce bottle (0.06 liter) wereplaced 3.95 gm Heloxy® 8 (trade name for a C12/C14 glycidyl ether ofapproximate 85% purity), 1.06 gm of 37% aqueous formaldehyde, 1.69 gm ofdi-n-butylamine, 1.29 gm of 37% aqueous hydrochloric acid, and 2.00 gmof methanol. The bottle was capped and placed in an oven at 60° C. for18 hours. The bottle was cooled to room temperature and contained aclear water soluble amber liquid. NMR analysis confirmed the conversionof starting materials to the same oxazolidinium compound as that made inExample 1.

PREPARATORY EXAMPLE 7

Example 1 was repeated at an oven temperature of 90° C. for 14 hourswith a similar conversion to the same oxazolidinium compound.

Many modifications may be made in the compositions and methods of thisinvention without departing from the spirit and scope thereof that aredefined only in the appended claims. For example, the exactoxazolidinium compounds may be different from those explicitly mentionedherein. Various combinations of gas hydrate inhibitors alone or togetherother than those described here are also expected to be useful. Further,oxazolidinium compounds used alone or together with mixtures of water,hydrocarbons and hydrate-forming guest molecules different from thoseexemplified herein would be expected to be successful within the contextof this invention. Additionally, preparatory methods different thanthose exemplified herein with respect to reactants and reactionconditions but nevertheless falling within the boundaries of theinventive method are still included. For instance, different aldehydes,ketones, secondary amines, halohydrins and epoxides from thoseexplicitly mentioned herein may be used, and further, reactionconditions different from those exemplified and specifically mentionedare also expected to be useful.

1. A method for preparing an oxazolidinium compound comprising reactingan aldehyde and/or a ketone with a secondary amine and a reactantselected from the group consisting of a halohydrin and an epoxide, underreaction conditions sufficient to produce an oxazolidinium compound. 2.The method of claim 1 where the aldehyde has from 1 to 20 carbon atomsand the ketone has from 3 to 20 carbon atoms.
 3. The method of claim 1where the halohydrin has the general formula

wherein X is selected from the group consisting of chlorine, fluorine,bromine or iodine; and wherein R_(A), R_(B), R_(C) and R_(D) are eachindependently selected from the group consisting of hydrogen,hydrocarbon substituents containing from 1 to 20 carbon atoms, andheteroatoms selected from the group consisting of oxygen, nitrogen,phosphorus and combinations thereof.
 4. The method of claim 1 where thesecondary amine has from 2 to 20 carbon atoms, may be linear, branchedor cyclic and may be substituted with alkyl groups, aryl groups,alkylaryl groups, and aryl groups substituted with alkoxy groups.
 5. Themethod of claim 1 where the reaction conditions comprise a temperatureranging from about ambient to about 120° C., and a pressure ranging fromabout ambient to that required to keep the reactants and solvents in theliquid phase.
 6. The method of claim 1 where the oxazolidinium compoundhas the structure:

where R is a hydrocarbon substituent containing from 1 to 20 carbonatoms, a hydrocarbon substituent containing from 1 to 20 carbon atomssubstituted with a heteroatom selected from the group consisting ofoxygen, nitrogen, phosphorus and combinations thereof; R₁ and R₂ eachindependently have 1 to 20 carbon atoms, may be linear, branched orcyclic; linear, branched or cyclic groups having 1 to 20 carbon atomssubstituted with alkyl groups, aryl groups, alkylaryl groups, and arylgroups substituted with alkoxy groups, and X is selected from the groupconsisting of chlorine, fluorine, bromine or iodine.
 7. A method forpreparing an oxazolidinium compound comprising reacting an aldehydeand/or a ketone with a secondary amine and a reactant selected from thegroup consisting of a halohydrin and an epoxide, at a temperatureranging from about ambient to about 120° C., and a pressure ranging fromabout ambient to that required to keep the reactants and solvents in theliquid phase to produce an oxazolidinium compound having the structure:

where R is a hydrocarbon substituent containing from 1 to 20 carbonatoms, a hydrocarbon substituent containing from 1 to 20 carbon atomssubstituted with a heteroatom selected from the group consisting ofoxygen, nitrogen, phosphorus and combinations thereof; R₁ and R₂ eachindependently have 1 to 20 carbon atoms, may be linear, branched orcyclic; linear, branched or cyclic groups having 1 to 20 carbon atomssubstituted with alkyl groups, aryl groups, alkylaryl groups, and arylgroups substituted with alkoxy groups, and X is selected from the groupconsisting of chlorine, fluorine, bromine or iodine.
 8. The method ofclaim 7 where the aldehyde has from 1 to 20 carbon atoms and the ketonehas from 3 to 20 carbon atoms.
 9. The method of claim 7 where thehalohydrin has the general formula

wherein X is chlorine, fluorine, bromine or iodine; and wherein R_(A),R_(B), R_(C) and R_(D) are each independently selected from the groupconsisting of hydrogen, hydrocarbon substituents containing from 1 to 20carbon atoms, and heteroatoms selected from the group consisting ofoxygen, nitrogen, phosphorus and combinations thereof.
 10. The method ofclaim 7 where the secondary amine has from 2 to 20 carbon atoms, may belinear, branched or cyclic and may be substituted with alkyl groups,aryl groups, alkylaryl groups, and aryl groups substituted with alkoxygroups.
 11. An oxazolidinium compound prepared by a method comprisingreacting an aldehyde and/or a ketone with a secondary amine and areactant selected from the group consisting of a halohydrin and anepoxide, under reaction conditions sufficient to produce anoxazolidinium compound.
 12. The oxazolidinium compound of claim 11 wherethe aldehyde has from 1 to 20 carbon atoms and the ketone has from 3 to20 carbon atoms.
 13. The oxazolidinium compound of claim 11 where thehalohydrin has the general formula

wherein X is selected from the group consisting of chlorine, fluorine,bromine or iodine; and wherein R_(A), R_(B), R_(C) and R_(D) are eachindependently selected from the group consisting of hydrogen,hydrocarbon substituents containing from 1 to 20 carbon atoms, andheteroatoms selected from the group consisting of oxygen, nitrogen,phosphorus and combinations thereof.
 14. The oxazolidinium compound ofclaim 11 where the secondary amine has from 2 to 20 carbon atoms, may belinear, branched or cyclic and may be substituted with alkyl groups,aryl groups, alkylaryl groups, and aryl groups substituted with alkoxygroups.
 15. The oxazolidinium compound of claim 11 where the reactionconditions comprise a temperature ranging from about ambient to about120° C., and a pressure ranging from about ambient to that required tokeep the reactants and solvents in the liquid phase.
 16. Theoxazolidinium compound of claim 11 having the structure:

where R is a hydrocarbon substituent containing from 1 to 20 carbonatoms, a hydrocarbon substituent containing from 1 to 20 carbon atomssubstituted with a heteroatom selected from the group consisting ofoxygen, nitrogen, phosphorus and combinations thereof; R₁ and R₂ eachindependently have 1 to 20 carbon atoms, may be linear, branched orcyclic; linear, branched or cyclic groups having 1 to 20 carbon atomssubstituted with alkyl groups, aryl groups, alkylaryl groups, and arylgroups substituted with alkoxy groups, and X is selected from the groupconsisting of chlorine, fluorine, bromine or iodine.
 17. Anoxazolidinium compound having the structure:

where R is a hydrocarbon substituent containing from 1 to 20 carbonatoms, a hydrocarbon substituent containing from 1 to 20 carbon atomssubstituted with a heteroatom selected from the group consisting ofoxygen, nitrogen, phosphorus and combinations thereof; R₁ and R₂ eachindependently have 1 to 20 carbon atoms, may be linear, branched orcyclic; linear, branched or cyclic groups having 1 to 20 carbon atomssubstituted with alkyl groups, aryl groups, alkylaryl groups, and arylgroups substituted with alkoxy groups, and X is selected from the groupconsisting of chlorine, fluorine, bromine or iodine.
 18. A method forinhibiting formation of hydrocarbon hydrates comprising contacting afluid including a mixture comprising water and hydrate-forming guestmolecules at gas hydrate forming conditions with an amount ofoxazolidinium compound effective to inhibit formation of hydrocarbonhydrates at the conditions, where the oxazolidinium compound is preparedby a method comprising reacting an aldehyde and/or a ketone with asecondary amine and a reactant selected from the group consisting of ahalohydrin and an epoxide, under reaction conditions sufficient toproduce an oxazolidinium compound.
 19. The method of claim 18 where theamount of the oxazolidinium gas hydrate inhibitor in the fluid rangesfrom about 0.01 to about 10 volume % based on the water present.
 20. Themethod of claim 18 where the aldehyde is has from 1 to 20 carbon atomsand the ketone has from 3 to 20 carbon atoms.
 21. The method of claim 18where the halohydrin has the general formula

wherein X is selected from the group consisting of chlorine, fluorine,bromine or iodine; and wherein R_(A), R_(B), R_(C) and R_(D) are eachindependently selected from the group consisting of hydrogen,hydrocarbon substituents containing from 1 to 20 carbon atoms, andheteroatoms selected from the group consisting of oxygen, nitrogen,phosphorus and combinations thereof.
 22. The method of claim 18 wherethe secondary amine has from 2 to 20 carbon atoms, may be linear,branched or cyclic and may be substituted with alkyl groups, arylgroups, alkylaryl groups, and aryl groups substituted with alkoxygroups.
 23. The method of claim 18 where the reaction conditionscomprise a temperature ranging from about ambient to about 120° C., anda pressure ranging from about ambient to that required to keep thereactants and solvents in the liquid phase.
 24. The method of claim 18where the oxazolidinium compound has the structure:

where R is a hydrocarbon substituent containing from 1 to 20 carbonatoms, a hydrocarbon substituent containing from 1 to 20 carbon atomssubstituted with a heteroatom selected from the group consisting ofoxygen, nitrogen, phosphorus and combinations thereof; R₁ and R₂ eachindependently have 1 to 20 carbon atoms, may be linear, branched orcyclic; linear, branched or cyclic groups having 1 to 20 carbon atomssubstituted with alkyl groups, aryl groups, alkylaryl groups, and arylgroups substituted with alkoxy groups, and X is selected from the groupconsisting of chlorine, fluorine, bromine or iodine.